Craft the World: Lonely Mountain

Summary pulled directly from Steam - Some text may only be applicable to Steam platform

DLC Lonely Mountain adds a new world type to the game. Monsters have occupied a dwarven fortress and it's up to you to take back their home.

You're playing to survive. You won't be able to obtain and process unlimited quantities of ore, food, and other resources. You'll need to explore the looted fortress, clear away the rubble, and open hidden stashes in search of anything that might be even the least bit valuable.

DLC features:

New campaign level designed for experienced players.
Dwarven fortress that looks like a large labyrinth of secret rooms.
Modified Tech Tree focused on repairing objects and equipment found inside the fortress.
Search for lathes and additional stockpiles to establish manufacturing and repair found objects.
New mechanic of the waves of monsters that appear out of the hidden passages inside the mountain.
Objects and structures in the new level can now be partially damaged or repaired.
New monsters and beasts as well as tons of new objects, structures, and building blocks.